Jenson Button was furious after "pathetic" backmarkers cost him valuable seconds as he missed out on a maiden Formula One victory by a whisker in the Monaco Grand Prix.

Button was just 0.4 seconds behind winner Jarno Trulli at the end of the race after an exciting finale saw the Englishman close relentlessly.

His chances of victory rested on a brave last-lap move but Minardi pay driver Zsolt Baumgartner got in the way to ruin that hope.

But Button was more upset about an incident with Toyota driver Cristiano da Matta, whom he accused of refusing to yield when being lapped.

Da Matta was given a drive-through penalty by race officials for ignoring blue flags, which are waved to order slower cars to allow faster rivals to lap them.

Button, who when told about the Brazilian's penalty replied "good", claimed da Matta had not played fair.

He said: "I was really struggling with traffic. I was sitting behind da Matta for three-and-a-half laps. I have never seen anything like it.

"It took a lap to get the blue flags out but he had blue flags for two-and-a-half laps. I will be having a word with him later because it is just not on, it is just pathetic."

Da Matta, whose penalty seemed to relate to an incident with Rubens Barrichello, felt hard done by and claimed his punishment had been a "mistake".

Da Matta, who went on to finish sixth, said: "I really think that the situation with the blue flags has to be looked into because our race was compromised a lot with the mistake that was made.

"I was only a couple of seconds behind Rubens so I was almost able to get out in front of him after my first pit stop. It was just unfortunate that we had this blue flag incident."

Toyota technical director Mike Gascoyne went a step further, claiming teams further down the grid are not given equal treatment.

The Englishman said: "I have to say the inconsistency in blue flags is appalling. Cristiano got a blue flag, moved over at the next corner and was then given a penalty.

"Ralf Schumacher was a lap behind in front of us for two or three laps, nothing was done and this has cost us points.

"There seems to be one rule for those at the front and one rule for the rest of us."

Trulli, who won his first grand prix from pole position after an exciting race which saw heavy accidents for team-mate Fernando Alonso and Sauber's Giancarlo Fisichella, also struggled when lapping cars.

The Renault driver felt he suffered more than most because as leader for most of the race, he was usually the first to encounter slower cars.

"What really penalised me through the race were the backmarkers," he said. "They were really bad. I lost several seconds a lap sometimes, they were just ignoring me. Most of us had the same problem but when you are leading you are the first to hit backmarkers and you are the first to lose most of the time."